Following either popular or celebrity fashion trends, more and more consumers use hair treatments to pursue fashionable hairstyles. The color treatments include hair coloring, highlighting, and bleaching. Although these hairstyle techniques greatly satisfy consumers' needs, they also cause severe hair damage, especially when the treatments are used repetitively. Moreover, various daily actions to the hair, for example hair brushing, hair blow-drying, and sun light exposure add more damage to the hair.
It is generally accepted that chemical treatment and/or UV exposure causes hair damage, which results in increased porosity and swelling of the hair cuticle. That is why hair becomes rough, coarse and dull when damage happens to the hair. Furthermore, hair looses its tensile strength when damage occurs in the hair's cortex, since the cortex is believed to be primarily responsible for the tensile properties of human hair. The cuticle of the hair is an important factor in torsional mechanical properties, but its contribution to bulk longitudinal mechanical strength is minor. Therefore, the measurement of tensile strength not only is an evaluation method of hair damage, but also an indication to determine if damage has penetrated to the cortex. One of the ways to restore natural quality of damaged hair is to recover its reduced tensile strength.
A method of treating hair that addresses at least some of the above-mentioned problems is therefore desired.